Brian Cashman has loudly signaled his intentions to upgrading the injury-ridden Yankee rotation. He accomplished that in an exchange of Vidal Nuno for Brandon McCarthy, two pitchers who are not what they seem.

On the surface, Brandon McCarthy has posted a 3-10 record this year, accompanied by an unsightly 5.01 ERA. However, as any competent fantasy owner knows, one of the first things you look for in a buy-low target is the difference between a pitcher’s ERA and his more skills-driven xFIP. The difference in McCarthy’s ERA and xFIP (2.89!) is the biggest in the major leagues. His skills are impeccable: He maintains a healthy strikeout rate (7.6 K/9), while walking nobody (1.6 BB/9) and keeping the ball on the ground at 55%.

That’s all masked by a horrific trifecta of bad luck: a .345 BABIP, a 67% left-on-base rate, and a 20% HR/FB rate that is by far the highest in baseball. In truth, Brandon McCarthy is an above-average pitcher who might well be finding his stride and peaking just as the Yankees have acquired him. There’s no doubt he upgrades the Yankee rotation this year.

On the other side of the ledger, few Yankee fans are weeping over the loss of Vidal Nuno. Nuno got his cup of coffee last year, posting a 2.22 ERA in his 20 innings — but this was the opposite of the McCarthy effect. Nuno had a ridiculously favorable BABIP (.219), strand rate (89%), and HR/FB% (6.5%). All that masked an
xFIP of 5.32, and voila: Nuno’s ERA in 78 innings this year is 5.42, with skills that are a bit better (4.41 xFIP) but still well below-average (113 xFIP-).

Nuno was a 48th-round pick, he made nobody’s list of top ten list of Yankee prospects, and he wasn’t going to figure it all out this year. Yet, where McCarthy is a free agent at the end of the year, Nuno is under team control for the next five seasons. That’s plenty of time for him to work his way into an average MLB starter or useful bullpen piece at a guaranteed below-market salary.

Nuno’s minor league record hints at some potential. He dominated every level from A- to AAA along the way to being promoted, striking out 5 times as many batters as he walked over the course of 5 seasons.

Cashman did what said he was going to do: he made this year’s rotation better — and he did it in a way that would make a savvy fantasy owner proud, trading a piece that wasn’t going to help this year for a guy whose smart-person’s stats reveal him to be way better than his silly-old-codger stats.

But unfortunately for Cashman, he plays in a keeper league with some annoying real life constraints. In real life, he has owners that set arbitrary, self-imposed salary caps. In real life, young team-controlled players are growing in value as other teams are catching up to the Yankees in spending and locking up their young stars long term. In real life, Brandon McCarthy has been in the league since 2005 without ever coming close to pitching 200 IP. He pitched 170 innings once and his next most prolific season was 135 innings long. It’s uncertain whether he’ll still be there if the Yankees make the playoffs, and even then he doesn’t start Game 1 or 2. Most importantly, in real life, McCarthy projects to be about a 1-win upgrade the rest of the year on a bad team that would need a lot more to become legitimate contender.

In a vacuum, this is a a shrewd deal by Cashman. In context, it’s another example of sacrificing longer-term stability to ensure short-term mediocrity and moderate relevance.